Wednesday, 3 July 2019

reflection - Laser, wire, and a circle of light



So, when I point a laser at a piece of wire (pointed at a specific angle), a circle of light appears on a wall behind it (see image below). I am trying to see why this happens and if there are any readings on this. Could anyone give some tips on what I should search for or any references?


enter image description here
(screenshot from this youtube video)


So this is a problem for a physics tournament, but I haven't tried it myself yet. However I have found a video depicting what I mean.



Answer



So I did it myself and figured it out. It's just really simple reflection.


enter image description here


Basically the wire acts as a mirror, albeit a curved one. Because the light from a laser is straight, we won't have messy light. When a laser reflects off of a flat surface, it keeps going straight. However when it reflects off a small curved surface (i.e a wire), the laser rays all go different ways, and create a circle of light.


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